The present invention relates to a scanning electron microscope and pattern composite inspection using the same.
In recent years, with such devices as semiconductor devices highly integrated and miniaturized, the width of a line pattern and the hole diameter of a hole pattern in the semiconductor device have been sized to 100 nm or less and a scanning electron microscope has been used exclusively for measuring critical dimensions of these constituent factors. On the other hand, in inspecting defects of the line pattern and the like, the measurement over the entire surface of a wafer within a short period of time is needed and therefore it suffices that the presence or absence of defects only is first known, without requiring the measurement of the accurate size of a defect, so that for defect inspection, the scanning electron microscope is not always employed but an optical microscope is used principally. It is to be noted that in the defect inspection, as a wide use method applicable to the optical microscope and the scanning electron microscope as well, a comparative inspection method and a method for setting up an area in which the inspection is stopped have been proposed as described in, for example, JP-B-7-37892, JP-A-5-46734 and JP-A-2000-183122.
Conceivably, as the high integration and miniaturization in the semiconductor device further advances in the future, the scanning electron microscope will be used also for the defect inspection. In that case, the critical dimension measurement cannot be considered as also filling the role of the defect inspection. This is because when, for example, a fine foreign matter generated in the preceding process step is deposited on the periphery of a line pattern or there occurs such a defect that a line pattern is partly deficient, the foreign matter/defect will not sometimes be reflected in the result of critical dimension measurement. The foreign matter/defect, however, greatly affects the performance of the semiconductor device and the like. Accordingly, a separate or independent defect inspection based on the scanning electron microscope is considered to be necessary.
But, expectantly, much time will be consumed to perform an independent defect inspection for the whole of a wafer, for example, and the defect inspection is substantially difficult to practice. On the other hand, in consideration of the fact that the critical dimensions have been measured by the scanning electron microscope, possible execution of the critical dimension measurement and the defect inspection as well with a single scanning electron microscope will be preferable for convenience sake.